Device and method for making a three-dimensional object

ABSTRACT

A device for the making of a three-dimensional object ( 3 ) by means of layer by layer consolidation of a powderlike construction material ( 11 ) by electromagnetic radiation or particle beam has a height-adjustable carrier ( 2 ), on which the object ( 3 ) is built, and whose horizontal dimension defines a construction field ( 5 ). Furthermore, an irradiation device ( 6, 9 ) is present for directing the radiation onto regions of an applied layer of the construction material within the construction field ( 5 ) corresponding to an object cross section ( 30 ). A control unit ( 10 ) controls the irradiation device ( 6, 9 ) such that the powder particles of the construction material ( 11 ) are bonded together at the sites where the radiation impinges on the construction material. A selective heating device ( 18   a,    18   b ) is designed so that any given partial surface ( 19 ) of the construction field ( 5 ) can be heated before and/or after to a plateau temperature, which is significantly higher than the temperature of at least a portion of the construction field ( 5 ) outside the partial surface ( 19 ). The control unit ( 10 ) actuates the selective heating device ( 18   a,    18   b ) such that the partial surface ( 19 ) has a predefined minimum distance (d) from the edge of the construction field ( 5 ).

The present invention pertains to an additive manufacturing device andmethod, in particular a device and a method for the making of athree-dimensional object by means of selective layer by layerconsolidation of powder like construction material by means of theapplication of energy.

A method of this kind is used for example for Rapid Prototyping, RapidTooling or Rapid Manufacturing. An example of such a method is knownunder the name “selective laser sintering or laser melting”. In this,powder is selectively consolidated by selective irradiation with a laserbeam, in that the thermal energy introduced into the material by thelaser beam is used to melt the material entirely or superficially sothat the powder grains have joined together after the ensuing cooldown.Besides laser radiation, other electromagnetic radiation or also anelectron beam for example can be used for the application of energy.

EP 1 583 626 B1 describes a device and a method by which objects aremade with high precision, despite the rather fast manufacturing speedsought. In particular, when consolidating a layer of a powder likeconstruction material in order to generate a cross section of the objectbeing produced, it is proposed to alternately aim the energy beam atdifferent regions of the cross section of the object. In particular,during the manufacturing process the powder layer to be consolidated isrecorded by means of a thermal imaging camera and after an analysis ofthe temperature distribution in the powder layer the temperature isspecifically corrected at individual places in the powder layer. Thecomputations required for this to determine the nature and manner ofpropagation of thermal energy after the energy input by the energy beammake the method relatively complicated, however.

Stresses which are supposed to be reduced by the method in EP 1 583 626B1 occur in objects manufactured by means of a generative layeredconstruction method especially when the temperature of the powder layer,before the energy beam impinges on it, lies substantially below thetemperature at which a consolidation of the powderlike material takesplace by the fusing thereof. Thus, such stress problems occur inparticular, but not only, with metallic powder materials.

Therefore the problem which the present invention proposes to solve isthat of providing an improved device and an improved method for themaking of three-dimensional objects. It should be possible to producestress-free parts preferably in the simplest possible manner.

The problem is solved by a device according to claim 1 and a methodaccording to claim 13. Further developments of the invention areindicated in the dependent claims. Here, devices can also be developedfurther by the features of the methods indicated below or in thedependent claims, or vice versa.

A device according to the invention for the making of athree-dimensional object by means of layer by layer consolidation of apowderlike construction material by electromagnetic radiation orparticle beam contains: a height-adjustable carrier, on which the objectis built, and whose horizontal dimension defines a construction field,an irradiation device for directing the electromagnetic radiation orparticle radiation onto regions of an applied layer of the constructionmaterial within the construction field corresponding to an object crosssection, and a control unit for controlling the irradiation device suchthat the powder particles of the construction material are bondedtogether at the sites where the electromagnetic radiation or particleradiation impinges on the construction material. In particular, aselective heating device is present, which is designed so that any givenpartial surface of the construction field can be heated to a plateautemperature. The plateau temperature is significantly higher than thetemperature of at least a portion of the construction field outside thepartial surface. The control unit is further designed so that itcontrols the selective heating device such that the partial surface hasa predefined minimum distance d from the edge of the construction field.

In such a device, it is not the entire construction field that needs tobe brought up to a high temperature in order to decrease the temperaturedifference between the fused material and its surrounding, especiallythe surrounding unconsolidated powder material, and consequently reducestress cracks. Instead, by a minimum distance from the edge of theconstruction field the device is protected against the high temperaturesin that the unconsolidated powderlike construction material surroundingan object being produced serves as an insulator. Furthermore, a powderlayer in the construction field can be heated selectively, i.e., only atselected sites.

The plateau temperature can be, e.g., a temperature of theunconsolidated construction material immediately prior to supplying theenergy for its consolidation. Furthermore, the plateau temperature canalso be a temperature which is adjusted so that an already consolidatedobject cross section only cools down slowly. Preferably, the plateautemperature is at most 200° C., especially preferably at most 150° C.and very specially preferably at most 100° C. less than an activationtemperature of the construction material, i.e., a temperature at whichthe powder particles are bonded together by modification of the chemicaland/or physical properties of the powder so that a solid results after acooling. Due to the preheating of the construction material to theplateau temperature as close as possible to the activation temperature,the energy put in by the irradiation device is used extensively for theactual consolidation process and not so much for the preheating of thepowder. In this way, the consolidation process can occur in an overallmore controlled manner.

Preferably, the control unit has a data storage medium, in whichmaterial parameter values with regard to a thermal behaviour of at leastone construction material, preferably various construction materials,are stored. This makes it possible in particular to control the heatingprocess in dependence on the construction material used in the device.Further preferably, the control unit in operation, i.e., during themanufacturing process, establishes the minimum distance d from the edgeof the construction field in dependence on the material parameter valuesstored in the data storage medium for the construction material beingused. In this way, it is possible to set the minimum distance from theedge of the construction field in dependence on the respectiveinsulating properties of a quantity of the unconsolidated constructionmaterial surrounding the object being produced.

Generally in the context of the invention the minimum distance from theedge of the construction field should be kept as small as possible so asnot to needlessly block space in the construction field. On the otherhand, this minimum distance should be adequately dimensioned to protectother regions of the device from damage due to overly high temperaturestress.

Preferably, the control unit in operation establishes the shape of apartial surface to be selectively heated, inter alia its shape and/ordimensions, in dependence on the shape of the object cross section to beconsolidated. In this way, the surface of the powder layer to be heatedby means of the selective heating device can be especially effectivelylimited to the absolutely necessary degree, which improves the energyefficiency.

Moreover, the control unit in operation preferably establishes a partialsurface such that its area extent is greater than that of the objectcross section to be consolidated. In this way, not only an object crosssection to be consolidated, but also a portion of the powder surroundingit is heated, so that the heat dissipation from the sites beingconsolidated at the edge of the object cross section is lessened. Thislikewise leads to a reduction of thermal stresses and/or prevents aninadequate consolidation of the powder at the edge of the object crosssection.

In one preferred embodiment of the invention, the selective heatingdevice in operation directs electromagnetic radiation, especially laserradiation, and/or particle radiation onto the surface of theconstruction material. In this way, a selective heating of theconstruction material can occur without the use of complicated addedstructures, such as heating hoses or heating resistors. Furthermore, theheating can occur with high position selectivity. Especially when laserradiation is used for the selective heating and this laser radiation hasthe same wavelength as that of the irradiation device, if the latteralso uses a laser, one can take the laser radiation for the selectiveheating from the same laser source as is used to generate theconsolidation radiation.

Preferably the construction field is surrounded by a container, and inaddition a cooling and/or heating device is also present for the coolingand/or heating of the container. Due to a heating of the container, heatcan be supplied additionally to the powderlike construction material, sothat the selective heating device can be smaller in dimension. By acooling of the container surrounding the construction field, heat can bedeliberately taken away and the parts of the device surrounding thecontainer can be protected against the heat in the construction field.Due to the cooling, stationary thermal conditions in particular can beestablished in the surrounding of the container, by cooling down acontainer wall to a given temperature value. Furthermore, due to asuitable cooling it is possible to reduce the aforementioned minimumdistance from the edge of the construction field. Such a reduction willbe effected preferably in dependence on the determined (i.e., measuredor calculated) cooling parameter values of the cooling.

The device for making a three-dimensional object can also have atemperature measuring device, which performs a temperature measurementat least in a partial region of the construction field, preferably nearits edge. Preferably, the control unit can then control the heat supplyby the selective heating device during the manufacturing process suchthat a minimum plateau temperature to which a partial surface of theconstruction field is heated lies in at least one operating state (i.e.,not necessarily during the entire manufacturing process in one layer,but rather as needed, even temporarily) above a temperature relayed bythe temperature measuring device to the control unit by a predefinedamount.

By the monitoring of the temperature, the heating of the constructionmaterial by means of the selective heating device can be specificallyadapted to the particular conditions in the device at a given time. Inparticular, the control unit too can control the selective heatingdevice such that the partial surface is heated to a minimum plateautemperature which lies at least 300° C., preferably at least 400° C.,especially preferably at least 800° C. above the temperature relayed bythe temperature measuring device to the control unit. In this way,depending on the construction material used, the plateau temperature canbe set to be as close as possible to the activation temperature.

Preferably, the control unit controls the selective heating device suchthat the latter heats a partial surface of the construction field atleast to the plateau temperature before and/or after the directing ofthe electromagnetic radiation or particle radiation of the irradiationdevice onto the construction material. In this way, the heating processof the construction material and/or the cooldown process after itsconsolidation can occur in a more controlled manner. Without theselective heating, temperature changes in the powder like constructionmaterial as the irradiation device sweeps over the construction fieldare more abrupt and larger.

In particular, the control unit can control the selective heating deviceso that it heats a partial surface of the construction field after thedirecting of the electromagnetic radiation or particle radiation of theirradiation device onto the construction material such that a cooldownrate in the partial surface is at least 30%, preferably at least 50%,especially preferably at least 70% less than without the action of theselective heating device. By means of a device designed in this way itis possible to delay the cooldown process after the consolidation of thepowder, which serves in particular to prevent stress cracks.

With a device according to the invention, a method for making athree-dimensional object by means of a layer by layer consolidation of apowderlike construction material by electromagnetic radiation orparticle radiation is possible, wherein an object is built on aheight-adjustable carrier, whose horizontal dimension defines aconstruction field, and electromagnetic radiation or particle radiationis directed with the aid of an irradiation device onto regions of adeposited layer of the construction material within the constructionfield corresponding to an object cross section, wherein the irradiationdevice is controlled with a control unit such that the powder particlesof the construction material are bonded together at the sites where theelectromagnetic radiation or particle beam impinges on the constructionmaterial. In particular, with a selective heating device, any givenpartial surface of the construction field is heated to a plateautemperature, wherein the plateau temperature is significantly higherthan a temperature of at least a portion of the construction fieldpresent outside the partial surface. Here, the control unit controls theselective heating device such that the partial surface has a predefinedminimum distance d from the edge of the construction field.

In particular, the minimum distance d can be established in dependenceon preliminary experiments in which the heat transmission ability of theconstruction material used in the process is determined. In this way,the heating of the construction material can be adapted specifically tothe construction material being used with its characteristic thermalproperties.

Further features and purposes of the invention will emerge from thedescription of exemplary embodiments with the help of the appendeddrawings.

FIG. 1 is a schematic, partly sectioned view of an exemplary embodimentof a device according to the invention for the layer by layer making ofa three-dimensional object which is suitable for carrying out a methodaccording to the invention.

FIG. 2 is a top view of the construction field of the device from FIG.1, showing as an example an object cross section currently beingconsolidated.

FIG. 3 illustrates a preliminary experiment to determine the heattransmission behaviour of the powder like construction material.

In the following, making reference to FIG. 1, an example of a device 100according to the invention is described, being suited to carrying out amethod according to the invention. In the device 100, an object 3 isbuilt up in a container 1 open at the top, having a wall 1 a. In thecontainer 1 there is arranged a carrier which can move in a verticaldirection V, whose schematically depicted carrier plate 2 closes off thecontainer 1 at the bottom and thus forms its bottom. Not shown in thefigure is a construction platform which may also be present between thelowermost layer of the object 3 and the carrier plate 2. In FIG. 1, theobject 3 being built in the container 1 is shown in an intermediatestate with several cross sections 30 already consolidated, wherein theobject 3 is surrounded by powderlike construction material 13 remainingunconsolidated, and represented as transparent in the figure.

The device 100 furthermore contains a supply tank 11 for a powderlikeconstruction material which can be consolidated by electromagneticradiation or particle radiation and an applicator 12, able to move in ahorizontal direction H, for the application of a layer of theconstruction material onto the most recently consolidated object crosssection 30 and the unconsolidated construction material surrounding itwithin a construction field 5, which is bounded by the container wall 1a. The device 100 furthermore contains an irradiation device in the formof a first radiation source 6, such as a laser, which generates a laserbeam 7, which is directed via a deflection device 9 onto a layer ofunconsolidated construction material previously deposited by theapplicator 12. In addition, a selective heating device 18 a, 18 b isprovided, which is formed for example from a second radiation source 18a together with another deflection device 18 b. The second radiationsource 18 a can emit a heating beam 18 c, for example, which can bedeflected by means of the deflection device 18 b onto any given partialsurfaces 19 of the construction field 5 (see FIG. 2), which is boundedby the container wall 1 a.

The second radiation source 18 a can either generate electromagneticradiation, i.e., it can be a laser in particular, or it can generateparticle radiation (such as electrons). In the latter case, thedeflection device 18 b would be an ion optics. If the heating beam 18 cis a laser beam, the second radiation source 18 a can optionally beomitted and in its place the first radiation source 6 can be used togenerate the heating beam 18 c. For this, the light intensity is thenexpediently reduced by means of a supplemental optics not shown in FIG.1 as compared to the light intensity of the consolidation beam 7.Alternatively or in addition, the quantity of heat introduced with theheating beam 18 c can also be adjusted via the speed with which it ismoved across the deposited layer of the construction material.

Furthermore, the device 100 contains a control unit 10, by which theindividual components of the device 100 are controlled in coordinatedfashion to carry out the construction process. The control unit cancontain a CPU, whose operation is controlled by a computer program(software). The computer program can be stored separately from thedevice on a storage medium, from which it can be loaded into the device,especially into the control unit 10.

The deflection device 18 b is designed so that the heating beam 18 c ofthe second radiation source 18 a can be deflected onto any given regionsof the construction field 5, in particular can be directed only onto oneor more partial surfaces 19 thereof, wherein the total area of allpartial surfaces 19 and in particular the area of a partial surface 19is less than the area of the construction field 5. In particular, thecontrol device 10 can be used to adjust the introduced thermal energy byaltering the power density at the point of impingement of the heatingbeam 18 c on the construction field 5 and/or by altering the scanningspeed of the heating beam 18 c. The heating device 18 a is dimensionedsuch that, possibly by sufficient focusing of the heating beam 18 cand/or a sufficiently slow movement of the heating beam 18 c across theconstruction field 5, at least so much energy can be introduced into theuppermost powder layer possibly consolidated already in portions thereofthat the temperature at the point of impingement of the heating beam 18c is significantly higher than in other regions of the constructionfield 5. By “significantly higher” it is preferably meant that thetemperature of the powderlike construction material at the point ofimpingement of the heating beam 18 c is at least 300° C., preferably atleast 400° C. and in some cases at least 800° C. above the temperatureof the construction material in regions of the construction field 5where no object cross section of the object to be made is situated, as arule in a margin region of the construction field 5.

Activation temperature here means a temperature at which the powderparticles bond together as a result of a chemical and/or physical changein their properties, for example in that the powder particles fuseentirely or only fuse superficially and sinter together. The activationtemperature is thus a limit temperature at which the constructionmaterial is substantially modified in its chemical and/or physicalstructure.

Furthermore, the control software in the control device 10 controls theheating beam 18 c such that the point of impingement of the heating beamonto the construction field 5 always has a minimum distance d from theedge of the construction field 5. This situation is shown in FIG. 2.Here, within the construction field 5 there is shown an object crosssection 30 being consolidated, which is covered by a partial surface 19,in which a heating of the construction material by means of the heatingbeam 18 c occurs. As can be seen, the edge of the partial surface 19 hasa minimum distance d from the edge of the construction field 5.

In order to reduce stresses in the object being made, a heating of apartial surface to a plateau temperature as close as possible to theactivation temperature is preferably sought, i.e. for example to aplateau temperature which is at most 200° C., more preferably at most150° C. and especially preferably at most 100° C. lower than anactivation temperature of the construction material (11). However, thefollowing points speak against a heating to too high a temperature:

-   -   The temperature should not be so high that a consolidation of        the powder material takes place.    -   The higher the temperature, the more energy-consuming the        heating process is.    -   The higher the temperature, the greater is the heat dissipation        to the edges of the construction field 5 and a possible harmful        impact on the other parts of the device for layer by layer        generative manufacturing, in FIG. 1 the laser sintering or        melting device.

By taking account of the heat dissipating properties of the particularconstruction material used, one can specifically establish the plateautemperature to which the powderlike construction material needs to bepreheated. This is because the better the heat supplied by theconsolidation beam 7 is dissipated by the construction material, theharder it is to bring about a consolidation with the consolidation beam7. Thus, the better the heat dissipation properties of the constructionmaterial, the closer the plateau temperature should be to the activationtemperature.

The minimum distance d to the edge of the construction field 5 is alsoinfluenced by the heat transmission properties of the powder. As alreadymentioned above, the powder within this distance shall ensure aninsulation toward the outside of the construction field 50. Thus, thebetter the heat transmission properties of the unconsolidated powderlikeconstruction material, the greater the minimum distance d should bechosen.

In one particular embodiment, the control unit 10 has a data storage, inwhich material parameter values regarding the heat transmissionproperties of the construction material to be used in a plannedproduction of one or more objects are stored. Then, during amanufacturing process, the control unit 10 can carry out the controllingof the selective heating device 18 a, 18 b in consideration of thesematerial parameter values.

Ideally, material parameters or material parameter values regarding aplurality of construction materials will be stored in the data storage,so that prior to the start of a construction process the control unit 10only needs to be informed as to the type of construction material beingused.

In one advantageous embodiment of the invention, prior to amanufacturing process for objects with the device 100 the heattransmission ability of the construction material is determined inpre-tests so that it can be used for determining (establishing) theplateau temperature and the minimum distance d.

For the determination of the thermal conductivity of powderlikematerials, first of all one can use the needle probe method of ASTMD5334-08. Here, a thin, elongated heating source (the needle probe) isinserted into a powder bed and heated with constant power. At the sametime, the temperature inside the source is recorded. The slower the risein the source temperature, the higher the thermal conductivity of thesample material.

Alternatively or in addition to the aforementioned method, the heattransmission ability of the construction material can be determined withthe following preliminary experiment described in regard to FIG. 3. FIG.3 shows in magnified view the container 1 of the device 100 along withthe carrier plate 2 arranged in it. On this carrier plate 2 is placed aheat-insulating base 32, on which a heating cylinder 33 and a measuringstick 34 having a defined distance Δ from the heating cylinder 33 arearranged. For the preliminary experiment, the entire container 1 isfilled with construction material 13 up to a filling height Z,coinciding with the height of the heating cylinder 33. Next, the heatingcylinder 33 is preheated, for example by inductive heating, to atemperature T_(V) which is 100° C., for example, below the desiredactivation temperature for the construction material 13 in the actualconstruction process to follow. Of course, a different temperature T_(V)can also be used, but the closer the temperature T_(V) to the activationtemperature, the more precise the findings of the preliminary experimentare as to the actual heat transfer capacity of the construction materialthat is present during the actual construction process.

In the measuring stick 34 there are temperature detection elements 35arranged at various heights. In FIG. 3 precisely three of these elementsare shown, but one can also use any given other number of temperaturedetection elements. After the end of the heating process to thetemperature T_(V) of the measuring cylinder 33, the temperaturedetection elements 35 are used to detect the temperature in dependenceon the time. The time change in the temperature is dependent on the heattransmission properties of the construction material 13 in the spacewith the distance Δ between the measuring stick 34 and the heatingcylinder 33.

For an even more precise measurement of the heat transmission propertiesof the powder 13, a plurality of measuring sticks 34 can also bearranged at various distances Δ₁ . . . Δ_(n) from the heating element33. The heating element 33 for example can be a cylinder, whose heightessentially agrees with the height of the most massive object being madein the subsequent construction process, or whose diameter essentiallyagrees with the maximum diameter parallel to the carrier plate 2 of themost massive object being made in the subsequent construction process.

Alternatively or in addition to the preliminary experiments justdescribed, the thermal conductivity of the construction material canalso be determined during the manufacturing process of objects.

For this, the temperature of the uppermost powder layer is measured atdifferent sites by means of a thermal imaging camera (IR camera) or apoint pyrometer whose detection surface is moved across the uppermostpowder layer. Since one knows at which points of the powder layer aconsolidation is being carried out with the consolidation beam 7 and/ora preheating is being carried out with the heating beam 18 c, one canuse the distances between the points of the powder layer where thetemperature was determined and the sites of the powder layer whereenergy is being supplied to obtain information about the heat transfercapacity of the powder.

Otherwise, one can also specifically determine the temperature at one ormore sites in the construction field 5 with the thermal imaging cameraor the point pyrometer and adapt the heating power to the locallypresent temperature in the target region 19 for the selective heating.

By measuring the temperature at one or more sites at a referencelocation in the construction field 5, preferably near the edge of theconstruction field 5 at a position where no powder is being consolidatedin any layer, one can also adapt the minimum distance d from theconstruction field margin in dependence on the measured values found. Inthis way, in particular, the region outside the construction field 5 canbe protected against damage from too large a temperature rise. But thetemperature at the reference location can also be used alternatively oradditionally for the control of the heat supply to the at least onepartial surface 19 by the selective heating device, so that a minimumplateau temperature to which the partial surface 19 of the constructionfield 5 is heated is a predetermined amount above a temperature relayedby the temperature measuring device to the control unit 10. The minimumplateau temperature is preferably at least 300° C., more preferably atleast 400° C., especially preferably at least 800° C. above thetemperature relayed by the temperature measuring device to the controlunit 10.

Optionally, the container, preferably the container wall, can beprovided with a heating and/or cooling device (not shown). A heatingdevice in this place enables an additional heating of the constructionmaterial, so that not as much heat needs to be supplied by the heatingbeam 18 c. A cooling device in the wall of the container 1 means thatthe temperature outside the container 1 is prevented from rising toexcessively high values. If one matches the heating power of the heatingbeam 18 c, the minimum distance d and the cooling power of the coolingfor the container to each other, one can achieve a stationarytemperature distribution.

Although in the preceding discussion a laser sintering device or lasermelting device has been described in detail, the invention can also beapplied to other devices for the making of three-dimensional objects bymeans of the action of an energy beam for the consolidation of apowderlike construction material. For example, the energy forconsolidating the powder can also be introduced by a two-dimensionalradiation source, such as an infrared heater. In addition, it is alsopossible to use a plurality of radiation sources for the consolidation.Moreover, one is not limited to electromagnetic radiation as theradiation for the consolidation of the construction material. Instead,it is also possible to use particle radiation, such as an electron beam.

Even though we have constantly spoken of a heating beam in the above, itis also possible not to supply the preheating energy in a partialsurface 19 of the construction field 5 by sweeping a beam across thepartial surface 19. Instead the preheating energy may be supplied by atwo-dimensional irradiation of the at least one partial surface 19 or bysweeping across the at least one partial surface 19 with a beam actionzone that is not pointlike, but instead has a predetermined lateraldimension and shape. For example, the partial surface 19 can be scannedwith an infrared radiator. One must distinguish this from thetwo-dimensional heating systems known in the prior art, which can beused to heat the powderlike construction material in the entireconstruction field, but can only achieve an insignificant temperaturerise in a freshly applied powder layer.

The supplying of energy with the heating beam can occur not only beforethe beginning of a consolidation process in a deposited powder layer,but also at the same time as the consolidation process. Furthermore, itis possible to irradiate such partial surfaces 19 of a deposited powderlayer with the selective heating device, which are distinguished in thatalready selectively consolidated powder material is present in powderlayers lying underneath them. In this way, one avoids too rapid alowering of the temperature of the consolidated construction material.This prevents cracks due to too fast a cooldown of the alreadyconsolidated powder material and thus too rapid a cooldown of parts ofan already consolidated object cross section. Preferably, the goal ofthe heating with the selective heating device is to make a cooldown ratein the partial surface(s) 19 at least 30%, preferably at least 50%,especially preferably at least 70% less than it would be without theaction of the selective heating device 18 a, 18 b.

As in the prior art, the entire powder layer within the constructionfield 5 can be preheated additionally with a nonselectivetwo-dimensional heating to a start temperature of, for example, 150° C.

Although this was not explicitly mentioned above in the description ofthe exemplary embodiments, it is not only possible to make one object ina manufacturing process, but also several objects can be made inparallel in the container 1. Where an object is mentioned above, such ina selective heating of an object cross section, such procedure can alsobe applied to all other objects being made in the manufacturing process.For example, if several object cross sections are present in a powderlayer, the powder is selectively heated in the regions of several,preferably all, object cross sections.

As emerges from what has been said thus far, a selective heating makessense preferably in those partial surfaces 19 which are almost identicalto the object cross section(s) to be consolidated in a freshly depositedpowder layer. Likewise, the selective heating can be limited to parts ofthe object cross section/object cross sections in which the most intensestresses are expected. One recognizes that the partial surfaces 19 to beheated with the selective heating device will preferably vary from onelayer to another. Furthermore, it should be noted that different partialsurfaces 19 in a freshly deposited layer (not necessarily assigned tothe cross sections of different objects) do not necessarily have to bebrought to the same plateau temperature.

In another possible embodiment, a selective heating of partial surfaces19 of a deposited powder layer is effected such that around eachselectively heated partial surface 19 there is a nonselectively heatedpowder layer, having at least a lateral dimension d perpendicular to theedge of the partial surface 19. In this way, an insulating region ofthickness d of nonconsolidated powder is created around each selectivelyheated partial surface 19. With this technique, it is possible to lessenthe mutual thermal influencing of partial surfaces 19, for example whenseveral objects are being made in parallel. As a result, themanufacturing process can be effected in more controlled fashion.

The method according to the invention and the device according to theinvention are especially suited to metallic construction materials. Butin addition to this, the method according to the invention also bringsbenefits when other construction materials are used, such as ceramic orplastic powders, especially a PAEK powder.

1. Device for the making of a three-dimensional object by means of layerby layer consolidation of a powderlike construction material byelectromagnetic radiation or particle radiation with: aheight-adjustable carrier, on which the object is built, and whosehorizontal dimension defines a construction field, an irradiation devicefor directing the electromagnetic radiation or particle radiation ontoregions of an applied layer of the construction material within theconstruction field corresponding to an object cross section, a controlunit for controlling the irradiation device such that the powderparticles of the construction material are bonded together at the siteswhere the electromagnetic radiation or particle radiation impinges onthe construction material, characterized by a selective heating device,which is designed so that any given partial surface of the constructionfield can be heated to a plateau temperature, which plateau temperatureis significantly higher than the temperature of at least a portion ofthe construction field outside the partial surface, wherein the controlunit is designed so that it actuates the selective heating device suchthat the partial surface has a predefined minimum distance from the edgeof the construction field.
 2. Device according to claim 1, wherein theplateau temperature is at most 200° C. less than an activationtemperature of the construction material.
 3. Device according to claim1, wherein the control unit has a data storage, in which materialparameter values with regard to a thermal behaviour of at least oneconstruction material, preferably various construction materials, arestored.
 4. Device according to claim 3, wherein the control unit inoperation establishes the minimum distance in dependence on the materialparameter values stored in the data storage for the constructionmaterial being used.
 5. Device according to claim 1, wherein the controlunit in operation establishes the shape of the partial surface independence on the shape of the object cross section to be consolidated.6. Device according to claim 1, wherein the control unit in operationestablishes the partial surface such that its area extent is greaterthan that of the object cross section to be consolidated.
 7. Deviceaccording to claim 1, wherein the selective heating device in operationdirects electromagnetic radiation, especially laser radiation, and/orparticle radiation onto the surface of the construction material. 8.Device according to claim 7, wherein the irradiation device directslaser radiation onto the surface of the construction material and thelaser radiation of the selective heating device has the same wavelengthas that of the irradiation device.
 9. Device according to claim 1,further comprising a container surrounding the construction field,wherein the device comprises a cooling and/or heating device for thecooling and/or heating of the container.
 10. Device according to claim1, further comprising a temperature measuring device, wherein thecontrol unit in operation controls the heat supply by the selectiveheating device so that a minimum plateau temperature to which thepartial surface of the construction field is heated in at least oneoperating state is by a predetermined amount above a temperature relayedby the temperature measuring device to the control unit.
 11. Deviceaccording to claim 10, wherein the control unit controls the selectiveheating device so that the partial surface is preheated to a minimumplateau temperature which lies at least 300° C. above the temperaturerelayed by the temperature measuring device to the control unit. 12.Device according to claim 1, wherein the control unit actuates theselective heating device so that it heats a partial surface of theconstruction field after the directing of the electromagnetic radiationor particle radiation onto the construction material by the irradiationdevice such that a cooldown rate in the partial surface is at least 30%less than without the action of the selective heating device, whereinthe partial surface has a predefined minimum distance from the edge ofthe construction field.
 13. Method for making a three-dimensional objectby means of a layer by layer consolidation of a powderlike constructionmaterial by electromagnetic radiation or particle radiation in a device,according to claim 1, wherein an object is built on a height-adjustablecarrier, whose horizontal dimension defines a construction field,wherein the electromagnetic radiation or particle radiation is directedwith the aid of an irradiation device onto regions of a deposited layerof the construction material within the construction field thatcorrespond to an object cross section, wherein the irradiation device iscontrolled with a control unit such that the powder particles of theconstruction material are bonded together at the sites where theelectromagnetic radiation or particle radiation impinges on theconstruction material, characterized in that, with a selective heatingdevice, any given partial surface of the construction field is heated toa plateau temperature, which plateau temperature is significantly higherthan a temperature of at least a portion of the construction fieldoutside the partial surface, wherein the control unit actuates theselective heating device so that the partial surface has a predefinedminimum distance from the edge of the construction field.
 14. Methodaccording to claim 13, wherein the minimum distance is established independence on preliminary experiments in which the heat transmissionability of the construction material used in the method is determined.15. Method according to claim 14, wherein the control unit actuates theselective heating device so that the latter heats the partial surface ofthe construction field at least to the plateau temperature before and/orafter the directing of the electromagnetic radiation or particleradiation onto the construction material by the irradiation device,wherein the partial surface has a predefined minimum distance from theedge of the construction field.
 16. Device according to claim 3, with atemperature measuring device, wherein the control unit in operationcontrols the heat supply by the selective heating device so that aminimum plateau temperature to which the partial surface of theconstruction field is heated in at least one operating state is by apredetermined amount above a temperature relayed by the temperaturemeasuring device to the control unit.
 17. Method for making athree-dimensional object by means of a layer by layer consolidation of apowder like construction material by electromagnetic radiation orparticle radiation in a device, especially according to claim 3, whereinan object is built on a height-adjustable carrier, whose horizontaldimension defines a construction field, wherein the electromagneticradiation or particle radiation is directed with the aid of anirradiation device onto regions of a deposited layer of the constructionmaterial within the construction field that correspond to an objectcross section, wherein the irradiation device is controlled with acontrol unit such that the powder particles of the construction materialare bonded together at the sites where the electromagnetic radiation orparticle radiation impinges on the construction material, characterizedin that, with a selective heating device, any given partial surface ofthe construction field is heated to a plateau temperature, which plateautemperature is significantly higher than a temperature of at least aportion of the construction field outside the partial surface, whereinthe control unit actuates the selective heating device so that thepartial surface has a predefined minimum distance from the edge of theconstruction field.
 18. Method for making a three-dimensional object bymeans of a layer by layer consolidation of a powder like constructionmaterial by electromagnetic radiation or particle radiation in a device,especially according to claim 5, wherein an object is built on aheight-adjustable carrier, whose horizontal dimension defines aconstruction field, wherein the electromagnetic radiation or particleradiation is directed with the aid of an irradiation device onto regionsof a deposited layer of the construction material within theconstruction field that correspond to an object cross section, whereinthe irradiation device is controlled with a control unit such that thepowder particles of the construction material are bonded together at thesites where the electromagnetic radiation or particle radiation impingeson the construction material, characterized in that, with a selectiveheating device, any given partial surface of the construction field isheated to a plateau temperature, which plateau temperature issignificantly higher than a temperature of at least a portion of theconstruction field outside the partial surface, wherein the control unitactuates the selective heating device so that the partial surface has apredefined minimum distance (d) from the edge of the construction field.19. Method for making a three-dimensional object by means of a layer bylayer consolidation of a powder like construction material byelectromagnetic radiation or particle radiation in a device, especiallyaccording to claim 6, wherein an object is built on a height-adjustablecarrier, whose horizontal dimension defines a construction field,wherein the electromagnetic radiation or particle radiation is directedwith the aid of an irradiation device onto regions of a deposited layerof the construction material within the construction field thatcorrespond to an object cross section, wherein the irradiation device iscontrolled with a control unit such that the powder particles of theconstruction material are bonded together at the sites where theelectromagnetic radiation or particle radiation impinges on theconstruction material, characterized in that, with a selective heatingdevice, any given partial surface of the construction field is heated toa plateau temperature, which plateau temperature is significantly higherthan a temperature of at least a portion of the construction fieldoutside the partial surface, wherein the control unit actuates theselective heating device so that the partial surface has a predefinedminimum distance from the edge of the construction field.
 20. Method formaking a three-dimensional object by means of a layer by layerconsolidation of a powder like construction material by electromagneticradiation or particle radiation in a device, especially according toclaim 10, wherein an object is built on a height-adjustable carrier,whose horizontal dimension defines a construction field, wherein theelectromagnetic radiation or particle radiation is directed with the aidof an irradiation device onto regions of a deposited layer of theconstruction material within the construction field that correspond toan object cross section, wherein the irradiation device is controlledwith a control unit such that the powder particles of the constructionmaterial are bonded together at the sites where the electromagneticradiation or particle radiation impinges on the construction material,characterized in that, with a selective heating device, any givenpartial surface of the construction field is heated to a plateautemperature, which plateau temperature is significantly higher than atemperature of at least a portion of the construction field outside thepartial surface, wherein the control unit actuates the selective heatingdevice so that the partial surface has a predefined minimum distancefrom the edge of the construction field.